Can a return spring be too strong? (Tappet plate)

So I have this issue with my tappet plate snaps and this has happened twice in the same gearbox. I’m running a jingji SLR gearbox with metal gear internals , 1.3 spring , and a element high torque motor, and a turning 11v battery.

So I have snapped both the normal and the black special jingji SLR tappet plate.

Could the high rpm motor be the problem or the return spring because the return print is one of those steel ones and is shorter than usual ones.

On a side note, the anti reverse latch spring has also snapped off twice.

Any ideas on these issues?


Apparently yes, a tappet spring can be too strong.

I’m not sure where I gleaned that info but the long and short was if it slams into the t piece with too much force it can bounce and create an seal issue.

As for your tappets breaking, it would seem possible that the stress of the spring could cause that.

Can’t say I’ve seen that before but then I have my own little bubble

Too strong a spring can stop the motor from turning the gears… a good 1.3 is about all a stock motor and standard gears can push… if the motor cant push the spring, dont keep your finger on trigger… things will melt …

You can try a delayer to dull the shock on the tappet plate… makes it less of a jerk action

Think he means the tappet return spring not the main spring

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correct, the return spring for the tappet plate. my motor is the element high torque spring which can pull a m150 spring. could this high RPM be the cause of the broken tappet plate too? if so what can i do to stop broken tappet plates but also have a decent RPM??


Metal tappet plate?
Won’t break :stuck_out_tongue: (just a little harsh on the nylon case maybe…)

Metal tappets are not great in my oppinion.


The M150 is designed for 2s Lipo and is a high torque motor not a high speed motor.
Even on 3s it isn’t a ridiculous rpm motor (36000rpm).
But the claimed max efficiency is at 20680rpm on a 2s Lipo so on a 3s battery if won’t be efficient and will eat batteries.
I would recommend this motor for higher ratio gear sets on 2s Lipo.

That being said I don’t think that is your problem.
Check the travel of your tappet and make sure it isn’t moving too far in either direction.
There are a few things that could make it travel too far.
Incorrect cylinder head or nozzel
Cam on the gears over extending it
Return spring way too strong

Try a weaker spring if you think that is the issue but I suspect it is something else.

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Had a similar question about return springs being to strong.

I just upgraded the cylinder, cylinder head and piston in my wells. Now the gears don’t seem to be able to pull the tappet back. The move freely until they engage the tappet, then just jam up. I’ve checked and checked and rechecked, everything is sitting in place and as should be, it’s got me stumped, it worked fine beforehand

You must have another issue, check the tappet is free to slide and does not jam with the box closed up.

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Yeah tappet moves freely manually.

Snapping 2 tappets does indicate an issue.
Metal will work well when cleaned of rough edges and contact points polished smooth.
Metal on nylon is popular in machinery as it is essentially self-lubricating.

Of you’ve snapped the tails off two it’s likely your sector gear is trying to pull them back beyond their limits and you may need to reprofile your tappet tail

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